Illustrative Mathematics
Find the Missing Angle
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
EngageNY
More on the Angles of a Triangle
Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...
EngageNY
Unknown Angle Proofs—Proofs with Constructions
Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...
EngageNY
Unknown Angle Problems with Inscribed Angles in Circles
We know theorems about circles—now what? Class members prove a theorem, with half the class taking the case where a point is inside the circle and half the class taking the case where a point is outside the circle. The lesson then...
Curated OER
Exploring Angle/Pair Relationships
Students find missing angles and sides of triangles. For this geometry lesson, students create intersecting lines to measure angles. They use Cabri Software to create virtual angles.
Curated OER
Angles
Students measure angles using a protractor. In this geometry lesson, students solve for the missing angles using equations set to the theorem of triangles. They measure missing angles through construction and identify congruent angles.
Curated OER
Triangle Side Lengths and Angles Measures
Students identify missing sides and angles. In this geometry lesson, students use triangular theorems to identify the missing sides. They use the Pythagorean Theorem to find the different ratios of each side.
Curated OER
Angle-Side Relationships
Students calculate the different sides and angles of a triangle. In this geometry lesson, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior angle theorem.
EngageNY
Looking More Carefully at Parallel Lines
Can you prove it? Making assumptions in geometry is commonplace. This resource requires mathematicians to prove the parallel line postulate through constructions. Learners construct parallel lines with a 180-degree rotation and then...
Utah Education Network (UEN)
Finding Missing Lengths of Similar Triangles
Middle and high schoolers explore the properties of similar triangles. In this geometry lesson, pupils play a similarity basketball game, sketch similar triangles, and find the missing measures of similar figures. They find the height of...
Curated OER
My Angle on Cooling
Students explore how the angle and distance of an object can change it's temperature. After reviewing how the position of the Earth affects the temperature of the planet, student groups design and perform an experiment to test how...
Curated OER
Measuring Body Angles
Students use technology to graph and compare angles. In this geometry lesson, students range of motion in the environment. They identify the missing parts of polygons using similarity and congruence.
Radford University
Developing a Trigonometry Phone App
What's one more app? After reviewing how to calculate missing side lengths or angle measures in a right triangle, pupils create instructions for a phone app to do all of the tedious work. They must consider all nine cases of known...
Curated OER
Triangle Exterior Angles Theorem
Students identify the measure of missing exterior angles. For this geometry lesson,students define and apply the exterior angle theorem to solve problems. They use Cabri software to create different angles and make investigations.
Curated OER
Angles in Triangles
Eighth graders translate word problems using mathematical ideas. In this geometry lesson plan, 8th graders identify angles of triangles using equations and the triangle sum theorem. They create angles with a protractor and straight edge.
Curated OER
Area Measures and Right Triangles
Your class will investigate the relationship among different triangles. This geometry lesson, demonstrates how to make a connection between triangles and the Pythagorean Theorem. They identify the missing side or angle of a triangle.
Curated OER
Light Bounce
Students solve problems involving triangles. In this geometry lesson plan, students apply properties of triangles to find the missing angles and sides. They identify angles of parallel lines cut by a transversal.
Curated OER
Trigonometric Ratios
Young scholars measure and analyze angles. In this trigonometry lesson, students measure angles and distances use non-traditional techniques. They identify the different ratios of sine, cosine and tangent.
EngageNY
Using Trigonometry to Find Side Lengths of an Acute Triangle
Not all triangles are right! Pupils learn to tackle non-right triangles using the Law of Sines and Law of Cosines. After using the two laws, they then apply them to word problems.
Curated OER
How are Trig Ratios Used to Measure Triangle Sides
Students identify the ratios of trig identities. In this geometry lesson, students solve the missing sides and angles of triangles using trig ratios. They relate the graphs and waves to real life scenarios.
Curated OER
The Law of Sines
Students define the laws of sine as it relates to a right triangle. In this trigonometry lesson, students identify the properties of sine to help then find mixing sides of a right triangle. They also solve for the missing angles.
Curated OER
Corresponding Parts of Similar Triangles
Here is a lesson that has learners take a look at corresponding parts of similar triangles, ratios of similarity, reductions and enlargements. They'll manipulate the scale factor (r) to observe the changes in similar triangles and then...
EngageNY
Solving Problems Using Sine and Cosine
Concepts are only valuable if they are applicable. An informative resource uses concepts developed in lessons 26 and 27 in a 36-part series. Scholars write equations and solve for missing side lengths for given right triangles. When...
Curated OER
Exploring Trigonometric Ratios
Students calculate the different ratios using a right triangle. In this trigonometry lesson, students identify the sine, cosine and tangent of each side. They find the missing angles using the different ratios.